diff --git a/client/jansson/error.c b/client/jansson/error.c
index 8532e04ff..dd4d1605f 100644
--- a/client/jansson/error.c
+++ b/client/jansson/error.c
@@ -24,7 +24,7 @@ void jsonp_error_set_source(json_error_t *error, const char *source)
 
     length = strlen(source);
     if (length < JSON_ERROR_SOURCE_LENGTH) {
-        strncpy(error->source, source, length);
+        strncpy(error->source, source, JSON_ERROR_SOURCE_LENGTH);
     } else {
         size_t extra = length - JSON_ERROR_SOURCE_LENGTH + 4;
         memcpy(error->source, "...", 3);